The present invention relates to a method and apparatus for controlling the yarn tension when cross-winding yarn onto a bobbin on a textile winding machine.
In one type of textile winding process, yarn from supply packages previously delivered to individual winding stations of a textile winding machine is unwound from supply packages and cross-wound onto bobbins in larger packages. If unwound at a constant winding speed, the yarn tension correspondingly increases as the unwinding continues. Frequently, the tensile force on the yarn during the time of unwinding of the last third to fifth of the yarn on the supply package represents the maximum tolerable winding speed. In general, the yarn is capable of handling the load increase resulting from an increase of the draw-off speed during the first 80% of the unwinding time. However, if the tension of the yarn is controlled to a substantially uniform value during the winding, the quality of the yarn on the larger packages can be improved or at least made more uniform. To this end, the winding speed is typically set at approximately that speed at which the maximum tolerable yarn tension occurs.
However, the setting of the winding speed at a predetermined constant value limits the productivity of each winding station since the yarn can, at certain times during the winding operation, be wound at a higher winding speed than the preset speed without the occurrence of yarn tension which exceeds the maximum tolerable tension amount.